Definition: Heterogeneous group of genetic disorders (classically divided in four types assessed by Sillence: I, II or congenital, III, and IV) characterized by severe bone fragility, leading to abnormal ossification and multiple fractures[1]. The 4 types are:

·Type I: does not present prenatal deformities, and the diagnosis is made after birth when the limb deformities start to develop.

·Type II: the most severe form: presents with multiple skeletal malformations, such as bone shortening and angulation, due to multiple fractures, demineralization of the skull, narrow and bell-shaped chest caused by fractures of the ribs, decreased fetal movement, wrinkling of the surface of the bones due to multiple fractures.

·Type III: less severe form than type II, usually presents multiple fractures at birth, with development of progressive bone deformities from neonatal period to adolescence. Detectable as early as second trimester in the Type IIIc.

·Type IV: this is the mildest presentation of the disorder, not detectable prenatally. It usually involved premature osteoporosis in the 4-5th decades of life.

Incidence: 0.4:10,000 live births and about half of it (0.19:10,000) represents Type II[3].

Etiology: In the majority of the cases of both Types I and IV, an autosomal dominant pattern is involved. Type II is a de novo dominant mutation (with a few reports of autosomal recessive pattern), and Type III is either autosomal recessive or dominant[4].

Recurrence risk: Depends on the form of transmission. In general, it ranges from 2-5% for type II, if it is not caused by a spontaneous mutation